Regulator for motor arc-lamps.



J. KlEFER.

REGULATOR FOR MOTOR ARC LAMPS APPLICATION mp0 JULY 20.1915.

Invntor' Johann K i efer,

sMQ

Hisf-Tttorneg.

UNITED STATE$ PATENT OFFICE.

JOHANN KIEFER, OF CHARLOTTEIQ'BURG, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

REGULATOR FOR MOTOR ARC-LAMPS.

Specification of Letters Patent.

Patented July 2, 1918.

Application filed July 20, 1915. Serial No. 40,979.

To all whom it may concern.-

Be it known that I, JoHANN KIEFER, a subject of the King of Bavaria, residing at Charlottenburg, Droysenstr. 18 Germany,

have invented certain new and useful Improvements in Regulators for Motor Arc- Lamps, oi. which the following is a specification.

My invention has reference to improvements in regulators for motor arc lamps; that is to'say, arc lamps in which the electrodes are controlled and the arc regulated by an electric motor. Lamps of this character are generally used for searchlights in which heavy currents and massive electrodes are employed. In accordance with my invention there is a direct current motor which is geared to the electrodes, whereby the latter are actuated to recede from or approach each other in accordance with the voltage prevailing between them. When there is no current on the lamp the motor armature is on open circuit, with respect to the line, but when current is turned on and passes between the electrodes, which are normally in contact, a series magnet controls a switch by which the armature circuit of the motor is closed across the line to receive current in a given direction; this causes the armature to rotate in a given direction, whereby the electrodes are separated and the arc is established. When the potentialof the arc has reached a predetermined normal value the armaturev circuit closed by the switch is opened and the armature is then closed upon itself through resistances whereby it is rapidly braked and whereby the arc length is limited. It then the electrodes are consumed and the arc becomes longer than is desired, a shunt magnet actuates the switch to close the armature circuit across the line in such manner as to receive current in the opposite direction, whereby the carbons are actuated to approach each other until the arc is again normal. When this happens the switch under control of the two magnets is again returned to its open position and the arma-- ture circuit, still closed upon itself through resistances, comes rapidly to a standstill. In thismanner the arc is maintained close to its normal length no matter whether the consumption of the electrodes is slow or fast.

The arrangement of the resistances in the armature braking circuit has as a consequence that when the armature takes current from the line in either one or the other direction, there is always a minor portion of the resistance in the armature circuit. This weakens the armature current, particularly when the armature is actuated to separate the carbons, at which time the voltage across the line is low. To obviate this diiilculty my invention provides means whereby when the armature is actuated to separate the carbons the minor resistance in the armature circuit is short circuited, so that the armature receives the full voltage that prevails between the electrodes until that voltage, by the separation of the carbons, has become high enough to furnish sufiicient working current to the armature through the resistance; and at this time that resistance is again thrown into the armature circuit.

All this will more fully appear from the following detail description with reference to the accompanyin drawing, which shows a diagram of the amp equipment except the gearing between the motor armature and the electrodes, this being so well known that it is not deemed necessary to illustrate the same.

Referring now to the drawing, 1 is the positive side and 2 the negative side of the line circuit, and the electrodes 3, 4 are in series in the line. In the drawing the electrodes are shown separated with the arc established between them, but it will be understood that when no current is on the lamp the electrodes are in contact. 5 is the armature of an electric motor and 6 is the field magnet of the same which is in a permanently closed shunt across the arc. Two

sets of resistances 7, 8 and 9, 10 are also each in a permanent shunt across the arc. 0f these resistances 7 and 9 are equal and so are the resistances 8 and 10, but the two companion resistances of each set, 7 and 8 and 9 and 10, need not be equal; in fact. it is preferable that they be unequal, and in the illustration here shown the resistance 8 is greater than resistance 7 and resistance 10 is greater than resistance 9, for a reason which will appear later on. The resistances 7 and 9 may properly be spoken of as minor resistances, in comparison with which the resistances 8 and 10 are major resistances. Two fixed contacts 11, 12 are connected by the conductors 13 and 1 1 with the main conductors 2 and 1 respectively, and between these two fixed contacts and normally out of contact with either is a pendulous switch arm 15, connected by a conductor 16 (a por tion of which is flexible, as at 17) between the two companion resistances 7 and 8, and with one brush of the armature; the other brush of the armature is connected by conductor 18 between the companion resistances 9 and 10., The pendulous arm 15 is the armature of the series magnet 19 and the shunt magnet 20, 'so that it can be actuated by one in one direction and. by the other in the opposite direction-"Whenactuated bythe series magnet 19 the pendulous switch arm makes contact -,with the stationary contact 12 and when actuatedby the shunt magnet 20 it makes contact with the stationary contactll.

The equipment so far described is complete in itself and operates as follows When there is no current on the lamp the electrodes are, as before stated, in contact, and when current is turned on the circuit is from side 1' of the line through series magnet 19, electrodes 3'4; to the side 2 of the line. The series electromagnet 19 is thereby energized andattracts the pendulous switch arm 15, which makes contact with the stationary contact12. This closes the motor armature circuit which now receives current, the course of which is from the side 1 of the main line, by conductor 14, contact l2, pendulous switch arm- 15, conductors 17 and 16, armature 5, conductor 18, minor resistance 9, to the other side 20f the line, in the direction indicated by the arrow.

a. The armature Iiow begins to rotate and separates the electrodes, gradually aining in power as the arc becomes longer, ecause the armature, being in a shunt. across the arc, has its current strength "increased as the arc voltage increases. But it will be seen that since the minor resistance 9 is in this armature circuit the armature does not receive the full benefit of the are voltage. Therefore, the motor starts'sluggishly. In a comparatively short time, however, the are attains its normal length and when this stage is reached the magnet 19 is suficiently weakened to allow the pendulous arm 15 to withdraw from contact 12 and assume its normal, middle position. This breaks the armature working circuit, but the armature by that time has attained high speed and should be stopped. It is'beingf stopped by the fact that the armature circuit is still closed, but this time u on itself by two parallel branches, one inc uding the resistances 7 and 9 and the other the resistances 8 and 10. These comparative short circuits of the armature act as a brake upon the same and thearmature is promptly arrested.

As by the gradual consumption of the electrodes the arc is lengthened, the shunt magnet 20 is energized gradually and eventually is strong enough to attract the pendulous arm 15 until the latter makes contact withthe fixed contact 11. This again closes the armature circuit which may now be traced fromthe side 1 of the line through major resistance 10, conductor 18, motor armature 5, conductors 16, 17, pendulous arm 15, contact 11, and by conductor 13 to the other side 2 of the main line. It will be seen that the current through the armature is HOWE in the direction of the arrow 5. Consequently, the armature is now rotated in the opposite direction, and,therefore, now operates to approach the electrodes to each other, until the arcis again at its normal length,

at which time the magnet 20 is. sufliciently deenergized to allow the pendulous arm 15 to again assume its middle position, thus breaking the armature working circuit at the contact 11. At this time too the armature has attained considerable speed and should be promptly arrested, and it is so arrested by the fact that it is still 'closed upon itself by the two parallel branches,

the electrodes are in contact. Therefore, the

minor resistance 9 is preferably made as small as practicable. When, on the other hand, the armature is actuated bycurrent' in the direction of the arrow 6 it may have i in its circuit the larger or major resistance 1'10 10, because at that time the arc is long, and, therefore, the difi'erence of potential under which the armature receives current is-high'.

It is desirable that when the armature is closed upon itself through its two parallel braking circuits that these two circuits have not too unequal resistances, and for this reason the minor resistance 9 cannot be made very small as would be desirable for the starting of the motor, when it is called upon to separate the electrodes, at which time, as herembefore indicated, it receives only low yoltage. To obviate thisv difliculty, which in some cases might be very inconvenient, I arrange a switch for short circuiting the minor resistance 9 when the motor is called upon to separate the electrodes For this purpose I provide a permanent shunt 21 etween the electrodes; that is to say, be-

tween the'two sides 1, 2 of the line, and in i this shunt there is a solenoid 22, the core of which is connected with a switch arm 23 Which in turn is connected with a retractile spring 24; and is so pivoted that it may make and break the continuity of a branch 25, which connects the conductor 18 with the side 2 of the main line, at the fixed contact 26. The solenoid 22 with its core is so proportioned with respect to the tension of the spring 24 that When the potential available for the permanent shunt 21 is low, so that the solenoid receives only very little current, the. spring 24 Will lift the core and With it the switch arm 23, until the latter bears upon the fixed contact 26 and thus closes the branch 25. When this happens the armature current in the direction a is from the side 1 of the line, by conductor 1%, contact 12, pendulous arm 15, conductors 17, 16, armature 5, branch 25, by switch arm 23 and fixed contact 26, to the side 2 of the line, thus shunting the minor resistance 9. Therefore, at the time when the armature, for the sake of efiective and rapid operation, should not be burdened even by the minor resistance 9, this resistance is short circuited and the armature receives the full voltage of the are. When this voltage increases by the lengthening of the arc, the core of the solenoid is drawn down, overcomes the tension of the spring 24, and branch 25 is opened at the contact 26. This is the condition which is shown in the drawing. No such provision for the removal of the major resistance 10 from the Working circuit of the motor armature is necessary when the Working current passes in the direction of the arrow 6, because at that time the potential available for the motor armature is comparatively high.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. An electric arc lamp, comprising a pair of electrodes, an electric motor for separating and for approaching the electrodes, two normally open shunts, each including the motor armature, across the electrodes, a minor resistance in one of these shunts, and a major resistance in the other, a series magnet for closing and opening the shunt containing the minor resistance to control the armature current in one direction, a shunt magnet for closing and opening the shunt containing the major resistance to control the armature current in the other direction, and means for short circuitin the minor resistance when the lamp potent1al drops below a predetermined minimum.

2. An electric arc lamp, comprising a pair of electrodes, an electric motor arranged to be energized by current depending upon the lamp potential and a resistance in the armature circuit for separating and approaching the electrodes, means for controlling the direction of the current through the motor armature by the lamp current and by the lamp potential, respectively, and for opening the armature working circuit when the arc length is normal, means for removing the resistance from the armature working circuit when the are potential drops below a predetermined minimum, and two branch circuits constantly closed about the armature for braking the motor when the armature Working circuit is opened While the armature rotates.

In witness whereof, I have hereunto set my hand this tenth day of June, 1915.

JOHANN KIEFER. 

